1. Field of the Invention
The present invention pertains generally to integrated circuit devices and preferred embodiments pertain generally to methods for manufacturing a hybrid integrated circuit device and, more particularly, to a hybrid integrated circuit device manufacturing method with which a plurality of circuit substrates are manufactured by dicing from a single, large-size metal substrate.
2. Description of the Related Art
The following description sets forth the inventors' knowledge of related art and problems therein and should not necessarily be construed as an admission of knowledge in the prior art.
A hybrid integrated circuit device from the related art shall now be described with reference to FIGS. 24(A)-(B). In this regard, FIG. 24(A) is a perspective view of a hybrid integrated circuit device 6. FIG. 24(B) is a sectional view taken along the line X-X′ of FIG. 24(A).
As illustrated in FIGS. 24(A) and 24(B), the existing hybrid integrated circuit device 6 has the following arrangement. The hybrid integrated circuit device 6 includes a rectangular substrate 60, a conductive pattern 62 formed on an insulating layer 61 that is disposed on the top surface of substrate 60, circuit elements 63 affixed onto the conductive pattern 62, metal wires 65 which electrically connect circuit elements 63 with the conductive pattern 62, and leads 64 which are electrically connected with the conductive pattern. The hybrid integrated circuit device 6 is completed as a product by sealing the hybrid integrated circuit formed on the top surface of circuit substrate 60 with an insulating resin or a case material, etc.
A method of manufacturing hybrid integrated circuit device 6 shall now be described with reference to FIGS. 25 to 27. First, a step of partitioning a large-size metal substrate 66A into elongated parts will be described with reference to FIGS. 25(A)-25(B). In this regard, FIG. 25(A) is a plan view of large-size metal substrate 66A and FIG. 25(B) is a sectional view of large-size metal substrate 66A. Now, a method of partitioning large-size metal substrate 66A into elongate parts will be described with reference to FIG. 25(A). As shown in FIG. 25(A), a large-size metal substrate 66A is partitioned into elongated parts along lines D4. This partitioning is performed by shearing using a shear force. The metal substrate that has been partitioned into elongated parts may be partitioned further into two or more parts in consideration of workability in a subsequent bonding step, etc. In the illustrated example, the metal substrate that has been partitioned into elongated parts is partitioned further into two metal substrates 66B that differ in length.
The arrangement of a metal substrate 66A shall now be described with reference to FIG. 25(B). As shown, the substrate 66A is formed of aluminum and both of its surfaces have been subjected to an alumite treatment. In addition, an insulating layer 61, for the insulation of the metal substrate 66A with respect to a conductive pattern, is provided on the surface on which a hybrid integrated circuit is to be formed. A copper foil 68, which becomes a conductive pattern 62 (shown in FIG. 26(B)), is press bonded to insulating layer 61.
A step of forming a hybrid integrated circuit 67 on the top surface of the metal substrate 66B that has been partitioned as an elongate part shall now be described with reference to FIGS. 26(A)-(B). In this regard, FIG. 26(A) is a plan view of an elongated metal substrate 66B on which a plurality of hybrid integrated circuits 67 have been formed. FIG. 26(B) is a sectional view of FIG. 26(A).
First, conductive patterns 62 are formed by etching copper foil 68 that has been press bonded onto insulating layer 61. Here, conductive patterns 62 are etched so as to form a plurality of hybrid integrated circuits on the elongated metal substrate 66B. In some cases, a resin overcoat is applied above the conductive patterns 62 in order to protect conductive patterns 62.
Solder or brazing material is then used to affix circuit elements 63 onto predetermined locations on each conductive pattern 62. Passive elements and active elements may be employed generally as circuit elements 63. In cases where a power transistor is mounted, the transistor is mounted onto a heat sink that is affixed to the conductive pattern.
A method of partitioning the metal substrate 66B, on which a plurality of hybrid integrated circuits 67 have been formed, into individual circuit substrates 60 shall now be described with reference to FIG. 27. As shown, individual circuit substrates 60, each having a hybrid integrated circuit 67 formed on a top surface, are partitioned from metal substrate 66B by punching out parts of the circuit substrate 60 using a press. In this regard, the press punches out the metal substrate 66B from the surfaces on which hybrid integrated circuits 67 are formed. In this manner, in order to carry out the punching operation, margins are provided around the peripheral end parts of circuit substrate 60, where margins conductive patterns 62 and circuit elements 63 are not formed.
After individually separating the circuit substrates 60 in the above step, the substrates are then completed as products by a step of sealing the hybrid integrated circuit 67, etc.
The above-described hybrid integrated circuit devices and the methods of manufacture thereof had a number of problems.
As a first problem, during the separation of a circuit substrate 60 from a metal substrate 66B by “punching” with a press, due to the impact of “punching,” cracks are often formed in the insulating layer 61 formed on the surface of circuit substrate 60.
As a second problem, the insulating layer 61 is formed on the top surface of metal substrate 66B, which insulating layer 61 is extremely hard since it is highly filled with alumina. As a result, there is the problem that the blade edge of the press for performing “punching” can wear quickly. Furthermore, productivity is lowered because an expert worker is needed to carry out the process of exchanging the blade edge of a press and because the exchange of the blade edge requires a very large amount of time.
As a third problem, when a circuit substrate 60 is separated from a metal substrate 66B by “punching” using a press, the peripheral parts of the metal substrate 66B create a loss of material. As a result, there is a large loss of metal substrate 66B material.
The present invention was made in view of the above and/or other problems in the related art.